Displacement sensors have been used for gauging parts on an assembly line, for use in orthopaedic implants, such as artificial hips and knees, for use on civil structures, such as buildings, dams, and bridges, and for use on vehicles. They have been limited, however, because of the bulk of some of the sensors for some of these applications. Biomedical implants, for example, must be as small as possible. Small displacement sensors are available from MicroStrain, Inc., and they have been described in commonly assigned U.S. Pat. Nos. 5,914,593, 6,433,629, 6,499,368 and 6,622,567 to MicroStrain, Inc. Shrinking these designs has been hindered by the need to maintain mechanical integrity in the face of potential lateral forces that could bend the moveable core or prevent its easy axial movement into the coil of the displacement sensor. Such problems would seriously degrade measurement accuracy.
However, further miniaturization has been needed to provide displacement sensors in applications requiring even smaller sizes.
Thus, a better solution is needed to provide further miniaturization for applications requiring extremely small sizes while still providing resistance to lateral displacement and lateral rotation from lateral forces, and this solution is provided by the following invention.